What time is it on the moon? US House space committee wants a standard lunar clock

Yahoo

24-05-2025

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We are one step closer to getting a lunar time zone this week, as a bill passed out of the US House Science, Space and Technology committee directs the administrator of NASA to develop a way to coordinate and measure time on the moon.
The bill is titled The Celestial Time Standardization Act (or HR 2313), and was passed out of committee by a voice vote on Tuesday (April 29). It now goes to the full House for a future floor vote. If it passes the House (and then the U.S. Senate), it would go to President Trump's desk, where it would be signed into law.
The bill will "require the Administrator of the National Aeronautics and Space Administration to develop celestial time standardization to support future operations and infrastructure on and around the Moon and other celestial bodies other than Earth, and for other purposes."
Specifically, the bill directs "The Administrator of NASA, in consultation with the Director of the Office of Science and Technology Policy, shall carry out the following: (1) Enable the development of celestial time standardization, including by leading the study and definition of a coordinated lunar time. (2) Develop a strategy to implement a coordinated lunar time that would support future operations and infrastructure on and around the Moon."
The bill further requires that NASA work with relevant public, private and academic institutions, international partners, and international standard-setting bodies to develop the new time system, with a few key requirements as guidance.
First, the new Coordinated Lunar Time (LTC) needs to be translatable into Coordinated Universal Time (UTC); it needs to be accurate enough for precision space navigation and communication; it needs to function uninterrupted during periods of loss of contact with Earth; and finally, the new time system needs to be scalable so that similar time systems can be established for other celestial bodies beyond the moon, especially Mars.
The issue of a dedicated time zone on the moon hasn't been given much attention in the past, as NASA and other agencies have previously used "mission elapsed time" and other timekeeping means to coordinate navigation and communication in cislunar space. However, as NASA and other space agencies have set their sights on new moon missions and establishing a permanent lunar presence, a common timekeeping system may be a good idea.
One major reason scientists can't simply use Earth time on the moon has to do with Albert Einstein's general relativity theory, which shows that gravity, mass and the passage of time are inextricably linked. All of our Earth clocks are therefore effectively set to Earth's gravity, while clocks on the moon would need to be set according to the much lower mass and gravity of the moon.
Time on the moon passes about 58.7 microseconds faster than on Earth, and when you're dealing with the kind of precision required for distant communication and navigation between the lunar surface and our planet, that difference (only about 58.7 millionths of a second) can cause real world problems.
With NASA facing some hefty proposed cuts to its funding this year and beyond, the unanimous voice vote to pass HR 2313 out of committee is encouraging for the future of NASA's Artemis mission, which aims to return humans to the moon in the next few years and ultimately establish a permanent base of the lunar surface. LTC would be necessary for any permanent operations on the lunar surface and in orbit around the moon.
This bipartisan support for Artemis was further demonstrated during the nomination hearing for Jared Isaacman, President Trump's pick to lead NASA, where both Republican and Democratic senators pressed Isaacman on his commitment to the program amid fears that he would prioritize Mars over returning to the moon.
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"We will prioritize sending American astronauts to Mars and along the way we will inevitably have the capabilities to return to the moon," Isaacman told the committee, adding later in his testimony that "We don't have to make a binary decision of moon versus Mars, or moon has to come first versus Mars."
Isaacman's nomination also passed out of the Senate committee this week, with both Committee Chairman Sen. Ted Cruz (R-TX) and Ranking Member Sen. Maria Cantwell (D-WA) supporting his nomination on the condition that Isaacman continue to pursue Artemis' program objectives.
"Mr. Isaacman seems to be committed to the current plan for both lander redundancies, Space Launch Systems, and returning to the Moon as fast as possible," Cantwell said.